import tkinter as tk

window = tk.Tk()
window.title("小A君")
window.geometry("200x100")

var = tk.StringVar()
l = tk.Label(window,textvariable=var,bg="green",font=("Arial",12),
             width=15,height=2)
l.pack()

on_hit = False

def hit_me():
    global on_hit
    if on_hit == False:
        on_hit = True
        var.set("you hit me")
    else:
        on_hit = False
        var.set("")
        
b = tk.Button(window,text = "hit me",width = 15,height=2,command = hit_me)
b.pack()

window.mainloop()
'''不断循环刷新'''

